Here are five truths of the wealthy that can be applied to your work ethic and investment strategy to help you think and grow richer, too.

1. Never quit.

"Before success comes in any man's life, he is sure to meet with much temporary defeat, and, perhaps, some failure. When defeat overtakes a man, the easiest and most logical thing to do is to quit. That is exactly what the majority of men do. More than five hundred of the most successful men this country has ever known told the author their greatest success came just one step beyond the point at which defeat had overtaken them." — Napoleon Hill, "Think And Grow Rich"

Napoleon Hill (1883-1970) believed wealth to be the physical manifestation of one's perseverance. In the book, "Think And Grow Rich," Hill tells the story of being three feet from gold, where out of frustration a gold miner sells his machinery to a junk man who then strikes it rich by digging just three feet away from where he had given up hope. "Think And Grow Rich" is truly an inspirational work of literature and one of the most widely read personal finance books in history. It also highlights the importance of persistence.

2. Invest for the long term.

"Most people overestimate what they can do in one year and underestimate what they can do in ten years." — Bill Gates

Bill Gates is founder of the Microsoft Corporation and has been the richest man in the world for the past two decades. His philosophy can be applied to any goal you're working to achieve in life, but in terms of investing, it is important to remember the benefits of long-term investments and the snowball effect of compound interest.

3. You don't need leverage.

Warren Buffett.AP / Seth Wenig"You really don't need leverage in this world much. If you're smart, you're going to make a lot of money without borrowing." — Warren Buffet

Warren Buffet is an investment guru, philanthropist, and the fourth wealthiest man in the world. The concept of using debt to build wealth is often counterproductive.

Remember, the measurement of one's net-worth is determined by the sum of one's assets minus debts.

In many cases, leverage (such as credit cards or personal loans) can slow the pace at which you accumulate real assets; even worse, using excessive leverage can damage your credit and imperil your ability to buy a house or start a business when you're ready.

4. Diversify.

"The other boys at Yale came from wealthy families, and none of them were investing outside the United States, and I thought, 'That is very egotistical. Why be so shortsighted or near-sighted as to focus only on America? Shouldn't you be more open-minded?" — Sir John Templeton

John Templeton (1912-2008) was an investment tycoon and philanthropist, and founder of Franklin Templeton Investments. Any good investment strategy will be well diversified and include international stocks in both established and emerging markets. Diversification reduces an investor's exposure to concentrated risks while attempting to maximize overall returns.

5. Love what you do.

"If you don't enjoy it, don't do it. You must love what you do." — Sir Richard Branson

Serial entrepreneur Richard Branson's Virgin brands span the globe. In the U.S. he is perhaps most widely known for Virgin Atlantic and Virgin Mobile. Like many of his billionaire cohorts, Branson believes if you follow your dreams and do what you love, success will follow and you'll live a much happier life. In Branson's case, that is now leading him to investing in space technologies.